The present invention relates to an outboard marine drive, and in particular to an outboard marine drive including an under cover and an engine cover for jointly defining an engine room both of which are made of plastic material.
An outboard marine drive typically defines a laterally narrow profile in a submerged part thereof to minimize the flow resistance, and a laterally broadest profile in a part where the under cover and engine cover are joined to each other to define an engine room therein. In such an outboard marine drive, it is desirable to form the under cover and engine cover with plastic material so as to minimize the weight of the outboard marine drive. However, to enable the outboard drive to support its own weight when placed on one side thereof, it is necessary to increase the thickness of the broad part thereof. However, this prevents the minimization of the weight of the outboard marine drive.
Also, a latch device is necessary for retaining the engine cover in the closed state. When the under cover is made of plastic material, it is required to be reinforced so as to be able to support the lock and/or latch device. This also prevents the minimization of the weight of the outboard marine drive.
The engine of the outboard marine drive is typically mounted on an engine mount case, for instance, made of aluminum alloy and provided with a high rigidity. Therefore, it is conceivable to resolve the problem of mechanical strength by forming the under cover integrally with the engine mount case.
However, the engine cover is required to have an open lower end of a relative large area so as to cover an upper part of the engine while permitting a favorable access to the engine when removed, and the under cover is required to have a correspondingly large open upper end which is adapted to engage the open lower end of the engine cover so as to jointly define an engine room. Therefore, if the under cover is made of metallic material, the weight of the outboard marine drive increases to an unacceptable level which would impair the handling such as transportation. In particular, as the size of the engine increases for an improved performance, the resulting increase in the overall weight of the outboard marine drive makes this problem all the more serious.
In larger outboard marine drives, the engine cover inevitably becomes large in size, and is required to be attached to the under cover or the engine mount case evenly at a plurality of points provided along the periphery of the lower open end of the engine cover. On the other hand, for servicing and other purposes, it is preferable to be able to remove the engine cover easily when required. Therefore, it is customary to provide a plurality of latch units along the periphery.
To eliminate the inconvenience of requiring to unlatch such latch units individually, it is preferable to provide a suitable synchronizing arrangement which enables a number of latch units to be unlatched simultaneously. Such latching arrangements have been proposed previously. For instance, Japanese patent laid open publication No.5-85484 discloses an arrangement in which a single inner cable actuates three latch units, Japanese patent laid open publication No.10-175595 discloses three hooks which are rotatable around horizontal shafts, one in a centrally front part and two on either side of a rear part, and Japanese utility model laid open publication No.59-54400 discloses an arrangement in which a pair of latch units are connected to each other by a Boden cable.
According to the proposal in Japanese patent laid open publication No.5-85484, because a single cable actuates all of the three latch units, a proper synchronization between the three latch units is not easy to achieve. Also, due to the absence of an outer tube for the actuation cable, the cable must extend substantially linearly between two of the latch units and the freedom in the layout of the latch units is limited so that an even pressure may not be applied to the seal member over the entire periphery of the engine cover.
According to the proposal in Japanese patent laid open publication No. 10-175595, the front and rear latch units must be released individually, and this inconvenience is not acceptable. Because the two hooks in the rear part are joined by a laterally extending rod, a laterally elongated space is necessary for passing the rod therethrough, and this severely limits the freedom in the layout of the latch units. This also prevents an even pressure to be applied to the seal member over the entire periphery of the engine cover.
According to the proposal in Japanese utility model laid open publication No. No.59-54400, the Boden cable extends along the inner surface of the engine cover, and it is difficult to adjust the tension of the cable so as to synchronize the actuation of the two latch units, and this work severely impairs the production efficiency and the ease of maintenance. This prior art reference does not teach how this proposal can be extended to the case where three or more latch units are required to be synchronized.
The lower edge of the engine cover engages the corresponding part of the engine under cover or the engine mount case via a seal rubber extending along the outer periphery of at least one of the two members which are to be joined to each other. During the closing and opening of the engine cover, the seal rubber tends to be excessively compressed each time the engine cover is attached in place, and this may cause a premature permanent deformation or other factors detrimental to the sealing performance of the seal rubber.
In view of such problems of the prior art, a primary object of the present invention is to provide an outboard marine drive which can achieve both a light weight and a high mechanical strength substantially without any compromise.
A second object of the present invention is to provide an outboard marine drive which is light in weight and can be safely placed on one side thereof.
A third object of the present invention is to provide an outboard marine drive which is light in weight and allows a secure attachment of latch devices for the engine cover.
A fourth object of the present invention is to provide an outboard marine drive which is provided with an improved latching arrangement for the engine cover.
A fifth object of the present invention is to provide an outboard marine drive which is provided with an improved sealing performance for the engine cover.
According to the present invention, these objects can be accomplished by providing an outboard marine drive, comprising: an internal combustion engine; an engine mount case made of metallic material for supporting the engine; an extension case depending from the engine mount case and accommodating at least a part of a power transmission unit therein; an under cover made of plastic material for covering a lower part of the engine, the under cover having a lower end attached to an upper end of the engine mount case and an open upper end; an engine cover made of plastic material for covering an upper part of the engine, the engine cover having a substantially enclosed upper end and an open lower end which is adapted to engage the open upper end of the under cover to jointly define an engine room; and a stay member, preferably made of metallic material, attached to a part supporting the engine and provided with an upper end disposed adjacent to an upper end of the under cover. Typically, the stay member is provided with a lower end which is fixedly attached to the engine mount case which supports the engine. Thus, the essential part of the under cover is reinforced by a metallic member.
Preferably, the stay member includes at least two substantially upright members extending substantially upright along an inner surface of the under cover, and a support rail is integrally attached to upper ends of the upright members and extending along an upper edge of the under cover. Such an arrangement allows a maximum mechanical strength to be achieved with a minimum weight. Thus, the open upper end of the under cover is reinforced by the stay member, and a desired rigidity and mechanical strength can be achieved while minimizing the weight of the outboard marine drive.
The support rail preferably extends substantially straight along an inner surface of a side of the under cover, and is integrally attached to the upper ends of the upright members so that the upright members and support rail jointly provide an adequate mechanical strength to support the outboard marine drive when the outboard marine is placed on a corresponding side thereof.
According to a preferred embodiment of the present invention, the support rail extends in an arcuate manner along a rear part of the under cover so as to conform to an inner profile of the under cover, and the support rail extend between upper ends of the upright members. The support rail may simply extend along the inner surface of the under cover without being attached thereto, but may also be attached to the under cover by threaded bolts or other fasteners if desired.
The stay member may also be used for supporting a part of a latch unit for retaining the engine cover in a closed state. The latch unit as used herein shall mean any arrangement for detachably joining two parts including, not exclusively, hooks, locks and other similar arrangements. The latch unit is preferably provided with a means for defining the fully closed position of the engine cover so that the excessive deformation of the seal rubber provided along the lower edge of the engine cover may be avoided. If such an excessive deformation is repeated, the sealing performance of the seal rubber may be impaired in time. Defining the fully closed position of the engine cover can be readily accomplished by providing an abutting part on the latch unit for engaging a corresponding abutting part of the striker or the engine cover for defining a closed position of the engine cover. Preferably, a resilient member is interposed between the abutting surface and the abutting part of the striker or the engine cover for the purpose of accommodating errors in the relative positioning of the abutting surface and the corresponding abutting part and providing a cushioning property.
As the size of the engine cover increases, it becomes necessary to attach it to the engine mount case or the under cover by using a plurality of latch units arranged along the outer periphery of the engine mount case or the under cover. These latch units can be conveniently synchronized by using a rigid link member.
Such an embodiment of the present invention additionally comprises at least a pair of strikers provided in a lower end of the engine cover; a corresponding number of latch units provided in parts of the engine mount case corresponding to the strikers, each of the latch units including a latch plate provided on the engine mount case for rotation in a substantially horizontal plane between a position for engaging a corresponding one of the strikers and a position for disengaging the striker; and a link member having a first end pivotally connected to the latch plate of one of the latch units and a second end pivotally connected to the latch plate of a different one of the latch units so that the latch plate of the one latch unit causes a like movement of the latch plate of the different latch unit for a synchronized actuation of the latch units. If desired, it may further comprise an under cover having a lower end attached to the engine mount case, and an upper open end adapted to engage the open lower end, and a stay member having an upper end located adjacent to the open upper end of the under cover, at least one of the latch units being mounted to the upper end of the stay member.
Alternatively or additionally, the latching arrangement for the engine cover in an outboard marine drive according to the present invention may further comprise at least three strikers provided in a lower end of the engine cover; a corresponding number of latch units provided in parts of the engine mount case corresponding to the strikers, each of the latch units including a latch plate provided on the engine mount case for rotation between a position for engaging a corresponding one of the strikers and a position for disengaging the striker; and at least a first cable and a second cable, the first cable having one end connected to the latch plate of a first one of the latch units and an opposite end connected to the latch plate of a second one of the latch units, and the second cable having one end connected to the latch plate of the second latch unit and an opposite end connected to the latch plate of the third latch unit, the cables being guided along a inner peripheral part of the engine mount case.